When plating articles with metal, e.g., copper, maintaining the concentration of the solution components relatively constant during use of the plating solution is important in order to provide uniform results from metal deposit to deposit. Since various plating components are continuously depleted from the solution, either by plate-out or by chemical reaction, it is necessary to replenish the solution by addition of a replenisher composition containing one or more of the depleted components. The replenisher is typically in the form of a concentrated solution of the depleted components. Addition of such replenisher solutions is well known in the art.
To accomplish replenishment in accordance with the prior art, the plating solution is circulated by means of suitable plumbing from a plating tank through a "controller" apparatus designed to (1) detect the concentration of various of the components in solution and (2) signal any depletion in concentration to a pump capable of supplying replenisher solution to the plating tank. Such apparatus as is currently available is expensive, occupies a considerable amount of space and requires that the solution be removed from the bath before it is analyzed for concentration so that there is some delay in obtaining data which occassionally results in the bath becoming over-replenished.
It is the purpose of this invention to provide apparatus which will enable control of the concentration of components within the plating solution without the inherent disadvantages of the currently available controller apparatus.